Substrate processing apparatus and substrate processing method

ABSTRACT

In a substrate processing apparatus for processing a substrate mounted on a mounting table in a processing chamber by supplying a gas to the substrate, the apparatus includes: a partition unit provided, between a processing space where a substrate is provided and a diffusion space where a first gas is diffused, to face the mounting table; a first gas supply unit for supplying the first gas to the diffusion space; first gas injection holes, formed through the partition unit, for injecting the first gas diffused in the diffusion space into the processing space; and a second gas supply unit including second gas injection holes opened on a gas injection surface of the partition unit which faces the processing space. The second gas supply unit independently supplies a second gas to each of a plurality of regions arranged in a horizontal direction in the processing space separately from the first gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application Nos.2017-065992 and 2018-019439 respectively filed on Mar. 29, 2017 and Feb.6, 2018, the entire contents of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present disclosure relates to a technique for performing processingby supplying a gas to a substrate accommodated in a processing chamber.

BACKGROUND OF THE INVENTION

A semiconductor manufacturing process includes plasma processing inwhich etching, film formation, or the like is performed by a plasma of areactant gas. As for an apparatus for performing such plasma processing,there is known a plasma processing apparatus disclosed in JapanesePatent Application Publication No. 2006-324023. In this plasmaprocessing apparatus, a plasma is generated by exciting a processing gasat an upper portion in a processing chamber and radicals that havepassed through an ion trap unit are supplied to a substrate.

When the processing gas is excited in the processing chamber during theplasma processing, there may be employed, e.g., a method for supplying ahigh frequency power to an antenna, generating an induced electric fieldin the processing chamber, exciting the processing gas supplied into theprocessing chamber, and supplying the excited processing gas to asemiconductor wafer (hereinafter, referred to as “wafer”). Since,however, the induced electric field for exciting the processing gas in aspace is not uniform, plasma distribution tends to be non-uniform.Further, plasma distribution is easily affected by a magnetic field oran electric field and it is difficult to control a density thereof.Therefore, it is difficult to obtain uniform in-plane distribution ofradicals supplied to the wafer. Recently, along with miniaturization ofa circuit pattern formed on a wafer, a higher accuracy is required forthe in-plane uniformity of the wafer processing. Accordingly, there isrequired a technique for controlling in-plane distribution of theprocessing on the substrate in a processing module.

Japanese Patent No. 5192214 discloses a technique for adjustingconcentration of a gas by supplying an additional gas to a peripheralportion of a wafer W and adjusting in-plane uniformity of the wafer W.However, it is disadvantageous in that the additional gas is difficultto be supplied to a central portion of the wafer W. In addition, anexample in which a processing gas is turned into a plasma and the plasmathus generated is supplied to the wafer is not considered.

SUMMARY OF THE INVENTION

In view of the above, the present disclosure provides a techniquecapable of adjusting in-plane uniformity of concentration of a gas insupplying the gas to a substrate in a processing chamber.

In accordance with an aspect, there is provided a substrate processingapparatus for processing a substrate mounted on a mounting table in aprocessing chamber by supplying a gas to the substrate. The substrateprocessing apparatus includes: a partition unit provided, between aprocessing space where a substrate is provided and a diffusion spacewhere a first gas is diffused, to face the mounting table; a first gassupply unit configured to supply the first gas to the diffusion space; aplurality of first gas injection holes formed through the partition unitin a thickness direction thereof and configured to inject the first gasdiffused in the diffusion space into the processing space; and a secondgas supply unit including a plurality of second gas injection holesopened on a gas injection surface of the partition unit which faces theprocessing space and configured to independently supply a second gas toeach of a plurality of regions arranged in a horizontal direction in theprocessing space separately from the first gas.

In accordance with another aspect, there is provided a substrateprocessing method using the substrate processing apparatus disclosedabove. The substrate processing method includes: etching a siliconnitride film formed on a surface of the substrate by activating thefirst gas supplied into the diffusion space and supplying the activatedfirst gas into the processing space; adjusting distribution of theactivated first gas in the processing space by supplying the second gasto the plurality of regions in the processing space; and supplying anoxide film removing gas for removing an oxide film on the surface of thesilicon nitride film from the first gas supply unit to the processingspace through the diffusion space or from the second gas supply unit tothe processing space.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present disclosure will become apparentfrom the following description of embodiments, given in conjunction withthe accompanying drawings, in which:

FIG. 1 is a plan view of a multi-chamber system according to a firstembodiment;

FIG. 2 is a vertical cross sectional view of a plasma processingapparatus according to the first embodiment;

FIG. 3 is a plan view of a shower plate when viewed from the top;

FIG. 4 is a plan view of the shower plate when viewed from the bottom;

FIG. 5 is a vertical cross sectional view of the shower plate;

FIG. 6 is a horizontal cross sectional view of the shower plate;

FIG. 7 is a cross sectional perspective view of the shower plate;

FIG. 8 is a cross sectional view of an ion trap unit;

FIG. 9 is a plan view of the ion trap unit;

FIGS. 10 and 11 explain an operation of the plasma processing apparatus;

FIG. 12 explains a shower plate in another example of the embodiment;

FIG. 13 is a cross sectional view of a wafer to be subjected to plasmaprocessing of the present disclosure;

FIGS. 14 and 15 explain an operation of another example of theembodiment;

FIG. 16 is a cross sectional view of a wafer after an etching process;

FIG. 17 is a plan view showing a top surface of a shower plate accordingto a second embodiment;

FIG. 18 is a plan view showing a bottom surface of the shower plateaccording to the second embodiment;

FIGS. 19 and 20 are vertical cross sectional views of the shower plateaccording to the second embodiment;

FIG. 21 is a vertical cross sectional view of a substrate processingapparatus according to a third embodiment; and

FIGS. 22 and 23 are plan views of a shower head according to the thirdembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(First Embodiment)

An example in which a substrate processing apparatus according to afirst embodiment is applied to a plasma processing apparatus will bedescribed. FIG. 1 shows a vacuum processing apparatus that is amulti-chamber system including a plasma processing apparatus. The vacuumprocessing apparatus includes a longitudinally elongated normal pressuretransfer chamber 12 set to a normal pressure atmosphere by a dry gas,e.g., a dry nitrogen gas. Three load ports 11 for mounting thereonrespective transfer containers C are arranged side by side in front ofthe normal pressure transfer chamber 12.

A door 17 that is opened and closed together with a lid of the transfercontainer C is attached to a front wall of the normal pressure transferchamber 12. A transfer mechanism 15 configured as a multi-joint arm fortransferring a wafer W is provided in the normal pressure transferchamber 12. Two load-lock chambers 13, for example, are arranged side byside at a side of the normal pressure transfer chamber 12 which isopposite to the side where the load ports 11 are provided. Gate valves18 are provided between the load-lock chambers 13 and the normalpressure transfer chamber 12. A vacuum transfer chamber 10 is providedat a rear side of the load-lock chambers 13, when viewed from the normalpressure transfer chamber 12 side, with a gate valves 19 providedbetween the vacuum transfer chamber 10 and each of the load-lockchambers 13.

Process modules 1 for performing, e.g., film formation, PHT (Post HeatTreatment) and plasma processing are connected to the vacuum transferchamber 10. A transfer mechanism 16 having two transfer arms, each beingconfigured as a multi-joint arm, is provided in the vacuum transferchamber 10. A wafer W is transferred between each of the load-lockchambers 13 and each of the process modules 1 by the transfer mechanism16. A cooling unit 14 for cooling the wafer W is connected to the normalpressure transfer chamber 12 in the vacuum processing apparatus. Forexample, a film forming apparatus forms a silicon nitride (SiN) film ona wafer W and a PHT apparatus sublimates reaction products generatedduring plasma processing by heating the wafer W subjected to the plasmaprocessing.

Next, among the process modules 1 provided in the vacuum processingapparatus, a plasma processing apparatus 2 will be described withreference to FIG. 2. Here, a plasma processing apparatus for etching theSiN film formed on the wafer W by using radicals generated by excitingnitrogen trifluoride (NF₃) gas, oxygen (O₂) gas, and (H₂) gas. Theplasma processing apparatus 2 includes a processing chamber 20 that is avacuum container made of metal such as aluminum or the like. As shown inFIG. 2, the plasma processing apparatus includes two processing chambers20 connected side by side in a right-left direction. A transfer port 22that is commonly used for two processing chambers 20 is formed at onesurface in a back-and-forth direction of the two connected processingchambers 20 to transfer the wafer W between the two processing chambers20 and the vacuum transfer chamber 10 shown in FIG. 1. The transfer port22 can be opened and closed by the gate valves 21.

As shown in FIG. 2, the connected processing chambers 20 are partitionedby a partition wall 23 provided at an upper side and a partition wall 24provided below the partition wall 23. The partition wall 24 isconfigured to be moved up and down by, e.g., an elevation mechanism 25.In a state where the partition wall 24 is lowered, processing spaceswhere mounting tables 3 of the two processing chambers 20 are providedcommunicate with each other and the wafer W can be loaded into each ofthe processing chambers 20. However, the two processing spaces arepartitioned from each other by raising the partition wall 24. The twoprocessing chambers 20 in the plasma processing apparatus 2 havesubstantially the same configuration. Therefore, one of the processingchamber 20 will be described hereinafter.

As shown in FIGS. 1 and 2, a mounting table 3 for horizontallysupporting the wafer W is provided in the processing chamber 2. Atemperature control passage 33 is formed in the mounting table 3. Atemperature control medium such as water or the like passes through thetemperature control passage. In radical treatment to be described later,a temperature of the wafer W is controlled to, e.g., about 10° C. to120° C. The mounting table 3 is provided with three elevating pins (notshown) spaced apart from each other at a regular interval in acircumferential direction and configured to project from a top surfaceof the mounting table.

A dielectric window 26 formed of, e.g., a quartz plate or the like, isprovided at a top plate portion of each processing chamber 20. A highfrequency antenna 27 formed of a spiral planar coil is provided on anupper surface of each dielectric window 26. A high frequency powersupply 29 for outputting a high frequency power of, e.g., 200 W to 1200W, is connected to an end portion of the coil-shaped high frequencyantenna 27 via a matching unit 28. The high frequency antenna 27, thematching unit 28, and the high frequency power supply 29 correspond to aplasma generation unit.

A gas supply port 34 for supplying a first gas is formed at eachprocessing chamber 20. One end of a gas supply line 35 is connected tothe gas supply port 34. The other end of the gas supply line 35 isbranched into three lines connected to an NF₃ gas supply source 36, anH₂ gas supply source 37, and an O₂ gas supply source 38, respectively.In FIG. 2, notations V1 to V3 represent valves and notations M1 to M3represent flow rate controllers. Accordingly, NF₃ gas, H₂ gas and O₂ gascan be supplied into the processing chamber 20 at predetermined flowrates. These gases supplied through the gas supply port 34 correspond tothe first gas.

Provided above the mounting table 3 in the processing chamber is apartition unit 5 for partitioning an inner space of the processingchamber 20 into a plasma space P where the NF₃ gas, the O₂ gas and theH₂ gas in the processing chamber 20 are diffused and a plasma is excitedand a processing space S where the wafer W mounted on the mounting table3 is subjected to radical treatment.

The partition unit 5 includes a shower plate 4 and an ion trap unit 51which are disposed in this order from a lower side. The shower plate 4and the ion trap unit 51 have different thermal expansion coefficientsand, thus, friction therebetween may generate particles. Accordingly,the shower plate 4 and the ion trap unit 51 are separated from eachother without contact by using, e.g., a spacer or the like.

The shower plate 4 will be described with reference to FIGS. 3 to 7.FIG. 3 shows the shower plate 4 provided in each processing chamber 20when viewed from the top. FIG. 4 is a plan view of the shower plate 4 inone of the processing chambers 20 when viewed from the mounting table 3.FIG. 5 is a vertical cross sectional view of the shower plate 4. FIG. 6is a horizontal cross sectional view of the shower plate 4 when viewedfrom the mounting table 3. FIG. 7 is a cross sectional perspective viewof the shower plate 4. Although ceiling surfaces of a gas diffusionpassage 45 and a gas introducing passage 405 formed in a flange 400 areclosed by a plate-shaped member, it is illustrated in FIG. 7 that theceiling surfaces of the gas diffusion passage 45 and the gas introducingpassage 405 are opened, for convenience of explanation. As will bedescribed later, a channel for supplying an inert gas, e.g., argon (Ar)gas, serving as a second gas is formed at a side of the shower plate 4which faces the processing space S. However, in FIG. 2, the crosssection of the shower plate 4 is indicated as oblique lines because ofdifficulty in drawing, and the channel to be described later is notshown. The shower plate 4 is, e.g., an aluminum plate. As shown in FIG.3, the shower plates 4 that partition the inner spaces of the respectiveprocessing chambers 20 are connected and configured as a singleplate-shaped body 40.

The flange 400 is formed around the shower plates 4 in the plate-shapedbody 40. The shower plates 4 are fixed by inserting the flange 400 intoa circumferential wall of each processing chamber 20. The heat of theshower plates 4 passes through an inner wall of the processing chamber20 via the flange 400 and is diffused. A coolant passage may be formedin the flange 400 so that the shower plates 4 can be cooled.

As shown in FIGS. 3 and 4, on the assumption that the processingchambers 20 are arranged in a right-left direction, in two semicircularregions obtained by dividing the shower plate 4 into two in theback-and-forth direction, slits 42 extending in a back-and-forthdirection and penetrating through the shower plate 4 in a thicknessdirection thereof are arranged in the right-left direction. As shown inFIG. 5, each of the slits 42 has a width greater than that formed in theion trap unit 51 to be described later, the width being increased towarda bottom opening thereof. A bottom end portion of an opening of each ofthe slits 42 is chamfered so that a decrease in a conductance of a gaspassing through the slits 42 is suppressed.

As shown in FIGS. 4 and 6, a gas supply path 43 is formed in the showerplate 4 to extend in the right-left direction (the arrangement directionof the processing chambers 20) between the semicircular regions wherethe slits 42 are formed. A plurality of central gas supply paths 44branched from the gas supply path 43 in a direction perpendicularthereto (back-and-forth direction) are each formed between the adjacentslits 42 in a circular region (central region) around the center of theshower plate 4. As shown in FIGS. 4, 6 and 7, an end portion on aperipheral side of the shower plate 4 in the gas supply path 43 isconnected to a central gas introducing port 402 formed in the flange400. An Ar gas supply source 48 is connected to the central gasintroducing port 402 through a central gas supply line 47. A flow ratecontroller M4 and a valve V4 are provided in the central gas supply line47 from an upstream side. As shown in FIGS. 4, 5 and 7, central gasinjection holes 41A that are opened on a gas injection surface, i.e., asurface of the shower plate 4 which faces the mounting table 3, aredistributed in the central gas supply path 44. The gas supply path 43,the central gas supply path 44, the central gas introducing port 402,the central gas supply line 47, the Ar gas supply source 48, the flowrate controller M4, the valve V4 and the central gas injection holes 41Acorrespond to a central gas supply unit.

As shown in FIGS. 4, 6 and 7, the gas diffusion passage 45 extending inan arc shape along the peripheral portion of the shower plate 4 isformed in the flange 400 at the front side and the rear side of theshower plate 4, and a peripheral gas supply path 46 branched from thegas diffusion passage 45 and extending in the back-and-forth directionis formed between the adjacent slits 42 in the peripheral region aroundthe central region of the shower plate 4. In each gas diffusion passage45, a connection passage 404 is extended from a longitudinal centerposition of the gas diffusion passage 45 toward a peripheral side of theplate-shaped body 40 in the back-and-forth direction. More specifically,the gas diffusion passage 45 has an arc shape as described above, andthe connection passage 404 is formed along a direction normal to thearc. An upstream end of the connection passage 404 is connected to aperipheral side gas introducing passage 405. The peripheral side gasintroducing passage 405 extends in a direction perpendicular to theextension direction of the connection passage 404 toward the centralportion in the right-left direction of the plate-shaped body 40. Anupstream end of the peripheral side gas introducing passage 405 isconnected to a peripheral side gas introduction port 403.

An enlarged view of the connection passage 404 and the gas diffusionpassage 45 is shown within a dotted circle indicated by an arrow in FIG.6. As shown in FIG. 6, a width d of the connection passage 404 issmaller than a width D of the peripheral side gas introducing passage405 (D>d). For example, the width D of the peripheral side gasintroduction path 405 is about 4 mm to 10 mm and the width d of theconnection passage 404 is about 2 mm to 6 mm. A length L of theconnection passage 404 is greater than the width d of the connectionpassage 404 by twice or more (L≥2d). The length L of the connectionpassage 404 is, e.g., about 4 mm to 12 mm.

The Ar gas supply source 48 is connected to the peripheral side gasintroduction port 403 through a peripheral side gas supply line 49. Aflow rate controller M5 and a valve V5 are sequentially provided in theperipheral side gas supply line 49 from an upstream side. As shown inFIGS. 4, 5 and 7, peripheral gas injection holes 41B that open to thesurface of the shower plate 4 which faces the mounting table 3 aredistributed in the peripheral gas supply path 46. The gas diffusionpassage 45, the peripheral gas supply path 46, the peripheral side gasintroduction port 403, the connection passage 404, the peripheral sidegas introduction path 405, the peripheral side gas supply line 49, theAr gas supply source 48, the flow rate controller M5, the valve V5, andthe peripheral gas injection holes 41B correspond to a peripheral gassupply unit. In FIG. 4, the central gas injection holes 41A areindicated by black dots and the peripheral gas injection holes 41B areindicated by white dots.

As shown in FIG. 8, the ion trap unit 51 includes, e.g., two quartzplates 51 a and 51 b arranged in a vertical direction. A spacer 52 madeof, e.g., quartz, is provided between the two quartz plates 51 a and 51b along the peripheral portion. The two quartz plates 51 a and 51 b faceeach other with a gap therebetween. As shown in FIGS. 8 and 9, aplurality of slits 53 and 54 penetrate through the quartz plates 51 aand 51 b, respectively, in the thickness direction thereof and extend inthe right-left direction. The slits 53 and 54 formed in the quartzplates 51 a and 51 b are alternately arranged without overlapping witheach other when viewed from the top. In FIGS. 3 to 9, the slits 42, 53and 54, the central gas injection holes 41A, and the peripheral gasinjection holes 41B are schematically illustrated. The arrangementinterval or the number of the slits and the injection holes are notaccurately illustrated.

In the first embodiment, the slits 42, 53 and 54 formed in the showerplate 4 and the ion trap unit 51 correspond to first gas supply holes.

Referring back to FIG. 2, a gas exhaust port 61 is opened on the bottomsurface of the processing chamber 20, and a gas exhaust line 62 isconnected to the gas exhaust port 61. A vacuum evacuation unit 6 such asa vacuum pump or the like is connected to the gas exhaust line 62through a pressure control valve, e.g., a pendulum valve or the like.Accordingly, a pressure in the processing chamber 20 can be reduced to apredetermined vacuum level.

As shown in FIG. 1, the vacuum processing apparatus includes a controlunit 9. The control unit 9 includes a program, a memory, and a CPU. Theprogram is stored in a computer storage medium, e.g., a compact disk, ahard disk, a magneto-optical disk or the like, and installed in thecontrol unit 9. The program includes a group of steps so that a seriesof processes including transfer of the wafer W and start and stop of gassupply in the plasma processing apparatus 2 can be performed.

The operation of the above embodiment will be described. For example,when the transfer container C containing the wafers W is loaded onto theload port 11 of the vacuum processing apparatus, the wafer W is takenout from the transfer container C and transferred to the vacuum transferchamber 10 through the normal pressure transfer chamber 12 and theload-lock chamber 13. Then, the wafer W is transferred to the filmforming apparatus and a SiN film is formed. Next, the wafer W is takenout from the film forming apparatus by the transfer unit 16 andtransferred to the plasma processing apparatus 2. In the plasmaprocessing apparatus 2, the wafer W is transferred by a cooperativeoperation of the elevating pins of each mounting table 3 and thetransfer unit 16 to be mounted on each mounting table 3. After the waferW as an etching target is loaded, the transfer unit is retreated to thevacuum transfer chamber and the gate valve 21 is closed. Then, thepartition wall 24 is raised and each processing chamber 20 ispartitioned.

Then, a pressure in each processing chamber 20 is set to, e.g. 13.3 Pato 133.3 Pa. NF₃ gas is supplied at a flow rate of 10 to 500 sccm. O₂gas is supplied at a flow rate of 10 sccm to 1000 sccm. H₂ gas issupplied at a flow rate of 5 sccm to 130 sccm. Ar gas is supplied at aflow rate of 50 sccm to 1000 sccm from the central gas injection holes41A and at a flow rate of 50 sccm to 1000 sccm from the peripheral gasinjection holes 41B. Accordingly, a mixture of the NF₃ gas, the O₂ gasand the H₂ gas fills the plasma space C in the processing chamber 20between the ion trap unit 51 and the dielectric window 26.

Thereafter, when a high frequency power of 200 W to 1200 W is appliedfrom the high frequency power supply 29 to the high frequency antenna27, an induced electric field is generated in the plasma space P, andthe NF₃ gas, the O₂ gas and the H₂ gas are excited. As a consequence, aplasma 100 of the NF₃ gas, the 02 gas and the H₂ gas is generated in theplasma space P as shown in FIG. 10. Since, however, the induced electricfield is generated in a donut shape, the density distribution of theplasma 100 generated in the plasma space P has a donut-shaped highdensity region.

Then, the plasma 100 passes through the slits 53 and 54 of the ion trapunit 51. Ions in the plasma 100 move anisotropically and thus aretrapped without passing through the slits 53 and 54 of the ion trap unit51. Radicals in the plasma move isotropically and thus pass through theion trap unit 51 and then pass through the shower plate 4. Accordingly,the plasma of the NF₃ gas, the O₂ gas, and the H₂ gas pass through theion trap unit 51, and then the concentration of radicals, e.g., F, NF₂,O, H and the like is increased.

The radicals such as F, NF₂, O and H that have passed through the iontrap unit 51 pass through the slits 42 of the shower plate 4 and enterthe processing space S. In the plasma space P, the concentration of theplasma 100 tends to be distributed in a donut shape. The radicals arerectified while passing through the ion trap unit 51. Therefore, theradicals having a uniform density enter the processing space 2 to besupplied to the wafer W. However, it is difficult to obtain a completelyuniform density even if the radicals pass through the ion trap unit 51and the shower plate 4, and the density distribution of the radicals isaffected by exhaust of the processing space S.

Then, the flow rate of the Ar gas supplied from the central gasinjection holes 41A and the flow rate of the Ar gas supplied from theperipheral gas injection holes 41B are adjusted. The flow rate of the Argas to be supplied to the region where the etching amount needs to berelatively low, between the central region and the peripheral region inthe processing space S, is relatively increased. For example, when theetching amount in the peripheral region of the processing space S needsto be lowered, the flow rate of the Ar gas at the peripheral region ofthe wafer W is increased and that at the central region of the wafer Wis decreased. Accordingly, in the processing space S, a ratio at whichthe radicals such as F, NF₂, O, H and the like are diluted with Ar gasis higher at the peripheral region of the wafer W than at the centralregion of the wafer W and, thus, the concentration of the radicals atthe center portion of the wafer W is relatively increased. As aconsequence, the concentration of radicals at the center portion of thewafer W and that at the peripheral portion of the wafer W become thesame, as shown in FIG. 11. As a result, the concentration distributionof the radicals 101 in the processing space S becomes uniform, and thein-plane uniformity of etching of the wafer W is improved. Thedistribution of the radicals such as F, NF₂, O, H and the like used forexciting the gas supplied from the first gas supply unit in theprocessing space S is adjusted by the Ar gas injected through thecentral gas injection holes 41A and the peripheral gas injection holes41B. Therefore, the Ar gas serving as the second gas may be referred toas a distribution adjusting gas for adjusting the distribution of thefirst gas.

In the processing space S, the SiN film is etched by the radicals suchas F, NF₂, O, H and the like. Then, the wafer W is transferred to thePHT apparatus by the transfer unit 16 and subjected to heat treatment.Accordingly, residues generated by the etching process are sublimatedand removed. Next, the wafer W is transferred to the load-lock chamber13 in a vacuum atmosphere. An atmosphere in the load-lock chamber 13 isswitched to an atmospheric atmosphere and, then, the wafer W is takenout from the load-lock chamber 13 by the transfer unit 15. Thetemperature of the wafer W is controlled by the cooling unit 14 and,then, the wafer W is returned to, e.g., the original transfer containerC.

In accordance with the above embodiment, in the plasma processingapparatus for processing the wafer W by supplying a gas to the wafer Win the processing chamber, the processing chamber 20 is partitioned bythe partition unit 5 into the plasma space P where the NF₃ gas, the 02gas and the H₂ gas are excited and the processing space S where theradical treatment is performed on the wafer W. Then, the NF₃ gas, the O₂gas and the H₂ gas excited in the plasma space P are supplied asradicals to the processing space S through the slits 53 and 54 formed inthe ion trap unit 51 and the slits 42 formed in the shower plate 4 and,also, Ar gas is separately supplied from the bottom surface of theshower plate 4. The Ar gas is supplied by the central gas supply unitfor supplying Ar gas from the central region side above the mountingtable 3 and the peripheral gas supply unit for supplying Ar gas from theperipheral region side above the mounting table 3. Therefore, the supplyamount of the Ar gas to the center portion of the mounting table 3 andthe supply amount of the Ar gas to the peripheral portion of themounting table 3 can be independently adjusted. Accordingly, it ispossible to adjust the in-plane distribution of the radicals supplied tothe wafer W. As a result, the in-plane distribution of the plasmaprocessing of the wafer W can be adjusted.

Depending on the supply positions of the NF₃ gas, the O₂ gas, and the H₂gas in the processing chamber 20, the concentration of the radicals ofthe NF₃ gas, the O₂ gas, and the H₂ gas may be increased at the centralregion in the processing space S. When the etching amount at the centralregion of the wafer W needs to be decreased, it is required torelatively increase the amount of Ar gas supplied from the central gassupply unit. Accordingly, the etching amount at the central region ofthe wafer W can be decreased compared to that at the peripheral regionof the wafer W.

Further, since the shower plate 4 can be configured as the plate-shapedbody 40, the scaling up of the apparatus can be avoided due to its thinthickness even in the case of using the shower plate 4 in combinationwith the ion trap unit 51.

In addition, there may be employed a plasma processing apparatus forsupplying a processing gas for converting NF₃ gas or the like to aplasma into the plasma space P and supplying NH₃ gas or the like fromthe bottom surface of the shower plate 4 to the wafer W withoutconverting it to a plasma. A plasma processing apparatus for removing anSiO₂ film by COR (chemical oxide removal) method may be used as anexample thereof. In this plasma processing apparatus, NH₄F that is anetchant is generated and adsorbed on the surface of the wafer W, andNH₄F and SiO₂ are made to react to produce AFS (ammoniumfluorosilicate). However, when NH₃ gas is turned into a plasma, NH₄F isnot generated. Therefore, NF₃ gas is supplied into the plasma space Pand converted to a plasma. The NH₃ gas is supplied from the bottomsurface of the shower plate 4 without passing through the plasma spaceP. In this example as well, by adjusting the supply amount of the NH₃gas supplied through the central gas injection holes 41A and the supplyamount of the NH₃ gas supplied through the peripheral gas injectionholes 41B, the in-plane distribution of the NH₃ gas can be adjusted andthe in-plane distribution of the supply amount of NH₄F on the surface ofthe wafer W can be adjusted. Accordingly, the same effect can beobtained.

When the plasma collides with the ion trap unit 51, the ion trap unit 51may accumulate heat. Radicals and the like passing through the ion trapunit 51 may be unevenly distributed due to the heat distribution. Thedistribution of radicals in the processing space S may be affected bythe heat distribution of the ion trap unit 51. In the above embodiment,the shower plate 4 is formed of an aluminum plate. By providing a heatshield member such as an aluminum plate or the like below the ion trapunit 51, it is possible to block radiation of the heat of the ion trapunit 51 into the processing space S. Therefore, it is possible tosuppress uneven distribution of the radicals in the processing space Sdue to the effect of the heat of the ion trap unit 51, and also possibleto accurately adjust the concentration distribution of the radicals inthe processing space S.

Since the shower plate 4 provided with the flange 400 is configured as aheat shield member and the flange 400 is made to be in contact with theprocessing chamber 20, the heat of the shower plate 4 is diffusedthrough the processing chamber 20. Accordingly, the heat shield effectis improved. Further, since the central gas supply path 44 and theperipheral gas supply path 46 which supply the second gas are providedin the shower plate 4, the heat of the shower plate 4 can be moreeffectively diffused by allowing the gas to flow through the central gassupply path 44 and the peripheral gas supply path 46. In the ion trapunit 51, the heat distribution varies depending on the plasmadistribution and the distribution of heat radiated to the processingspace S also varies. Therefore, by independently supplying the gas tothe central gas supply path 44 formed in the central portion of theshower plate 4 and the peripheral gas supply path 46 formed in theperipheral portion of the shower plate 4, the region where the gas flowsthrough the shower plate 4 can be changed in accordance with the heatdistribution of the ion trap unit 51. Accordingly, the heat of theshower plate 4 can be diffused more effectively.

As described with reference to FIG. 6, the peripheral gas introductionpath 405 is connected to the position bisecting the gas diffusionpassage 45 in the longitudinal direction and, thus, the flow rate of thegas in the right-left direction of the gas diffusion passage 45 can bedistributed with high uniformity. Since the gas distributed from the gasdiffusion passage 45 flows into each of the peripheral gas supply paths46, the gas can be injected with high uniformity through the peripheralgas injection holes 41 formed at the downstream side of the peripheralgas supply path 46.

Here, in the peripheral gas introduction path 405, the gas flows towardone side in the right-left direction. Therefore, compared to theconfiguration in which a downstream end of the peripheral gasintroduction path 405 is directly connected to the longitudinal centerportion of the gas diffusion passage 45, i.e., the configuration inwhich a gas is introduced into the gas diffusion passage 45 withoutpassing through the above-described connection passage 404, theconfiguration shown in FIG. 6 in which a gas is supplied to theconnection passage 404, rectified in the direction normal to thecircular arc and then introduced into the gas diffusion passage 45 ispreferable because it allows the gas to be more uniformly diffused inthe right-left direction in the gas diffusion passage 45.

In order to improve straightness of the gas by eliminating deflection ofthe gas flow in the connection passage 404 and increase uniformity ofgas distribution in the gas diffusion passage 45, it is preferable thatthe width d of the connection passage 404 is smaller than the width D ofthe peripheral gas introduction path 405. Further, in order to eliminatethe deflection of the gas flow in the connection passage 404 asdescribed above, it is preferable that the connection passage 404 has alength L that is greater than the width d by twice or more (L≥2d) asdescribed above.

It is also possible to expand the downstream end portion of theperipheral gas introducing passage 405 compared to the upstream endportion thereof and make the gas flowing into the connection flowpassage 404 stagnate temporarily at the downstream end portion of thegas introducing passage 405 and then flow into the connection passage404. With this configuration, it is possible to allow the gas to flowinto the connection passage 404 at a reduced flow velocity. Accordingly,the straightness of the gas in the connection passage 404 is improved.

In the present disclosure, the gas supplied through the central gasinjection holes 41A and the peripheral gas injection holes 41Bconstituting the second gas supply unit may be switched among differentkinds of gases. For example, as shown in FIG. 12, Ar gas and hydrogenfluoride (HF) gas for removing an oxide film can be independentlysupplied to the central gas introducing port 402 and the peripheral gasintroduction port 403 constituting the second gas supply unit. Asubstrate processing apparatus 1A capable of supplying Ar gas and HF gashas the same configuration as that of the plasma processing apparatus 2,except in that Ar gas and HF gas can be supplied to the ports 402 and403. In FIG. 12, a reference numeral 480 denotes a HF gas supply source;notations V7 and V8 denote valves; and notations M7 and M8 denote flowrate controllers.

FIG. 13 shows the wafer W that is a target substrate to be processed bythe substrate processing apparatus 1A. This wafer W is used for forming,e.g., a device having a 3D NAND structure. In this wafer W, a siliconnitride film (SiN film) 200 and a silicon oxide film (SiO₂ film) 201 arealternately laminated multiple times and a memory hole 202 is formedtherethrough. Before the processing of the substrate processingapparatus 1A, a thin natural oxide film 203 is formed on surfaces of theSiN films 200 which form a sidewall of the memory hole 202. Hereinafter,the processing of the substrate processing apparatus 1A will be brieflydescribed. After the natural oxide film 203 is removed, a surface layerof the SiN film 200 forming the sidewall of the memory hole 202 isetched. However, after this etching process, an oxide film may be formedon the surface of the SiN film 200. In that case, a film may not benormally filled in the memory hole 02 in a subsequence process.Therefore, in this substrate processing apparatus 1A, the oxide film isremoved after the etching so that the film can be normally filled.

An example of substrate processing using this substrate processingapparatus 1A will be described in detail. First, when the wafer W shownin FIG. 13 is provided in the substrate processing apparatus 1A, thenatural oxide film 203 on a side surface of the memory hole 202 isremoved. In that case, the processing chamber 2 is exhausted and thehigh frequency power supply 29 is switched off. In that state, as shownin FIG. 4, HF gas is supplied into the processing space S through thecentral gas injection holes 41A and the peripheral gas injection holes41B formed in the shower plate 4. In FIGS. 14 and 15, open valves areindicated in white and closed valves are Indicated in black. At thistime, the flow rate of the HF gas supplied to the central gasintroducing port 402 for introducing the gas to the central gasinjection holes 41A may be the same as the flow rate of the HF gassupplied to the two peripheral gas introduction ports 403 forintroducing the gas into the peripheral gas injection holes 41B. Due tothe action of the HF gas supplied into the processing space S asdescribed above, the natural oxide film 203 formed on the inner surfaceof the memory hole 202 is removed.

Next, as shown in FIG. 15, H₂ gas that is a modifying gas for modifyingthe SiN film 204 is supplied from the H₂ gas supply source 37 into theplasma space P, and the supply of the HF gas into the processing space Sis stopped. The high frequency power supply 29 is switched on to excitethe plasma. Therefore, H₂ gas is activated in the plasma space P, and Hradicals are supplied to the wafer W. Due to the action of the Hradicals, SiN bonds in the SiN film 200 are cut off. Accordingly, theSiN film 200 becomes to be easily etched (the SiN film 200 is modified).

Thereafter, as described with reference to FIGS. 10 and 11, the etchingprocess of the SiN film 200 is performed as the processing of the plasmaprocessing apparatus 2. Accordingly, the SiN film 200 forming thesidewall of each memory hole 202 is etched while ensuring high in-planeuniformity of the wafer W. When the SiN film 200 exposed in the memoryhole 202 is etched to a thickness of several nm, the etching iscompleted. The etching of the SiN film 200 is performed to improve thefillability of a film filled in each memory hole 202. After the etchingis completed, an oxide film 204 is formed on the surface of the SiN film200 forming the side wall of the memory hole 202 by the action of O₂ gasused for the etching, as shown in FIG. 16.

Therefore, as for after-treatment, as in the process of removing thenatural oxide film 203, the supply of the gas into the plasma space P isstopped and HF gas is supplied through the gas injection holes 41A and41B of the shower plate 4 in a state where the high frequency powersupply 29 is switched off as shown in FIG. 14. Accordingly, the oxidefilm 204 formed on the surface of the SiN film 200 can be removed.

After the removal of the oxide film 204, the wafer W is heated andresidues adhered to the wafer W are removed as described in the aboveembodiment, for example. The heating of the wafer W may be performed bythe PHT apparatus as described above or may be performed by thesubstrate processing apparatus 1A including a heating unit provided atthe mounting table 3.

By using the substrate processing apparatus 1A, the SiN film 200 can beetched with high uniformity in the plane of the wafer W. In addition,since the oxide film 204 on the surface of the SiN film 200 is removedafter the etching, it is possible to allow the film to be normallyfilled in the memory hole 202.

By using the substrate processing apparatus 1A, a series of substrateprocessing such as the removal of the natural oxide film 203, thepre-treatment for making the etching easier by cutting off the SiNbonds, and the removal of the oxide film 204 after the etching can beperformed in the same processing chamber 20. Therefore, when theabove-described series of substrate processing is performed, it is notnecessary to transfer the wafers W between the multiple processingchambers 20, which makes is possible to improve the throughput. Only theremoval of the natural oxide film 203 and the etching may be performedby the substrate processing apparatus 1A. Alternatively, only theetching and the removal of the oxide film 204 may be performed in thesubstrate processing apparatus 1A.

In the removal of the natural oxide film 203 as the pre-treatment of theetching or the removal of the oxide film 204 as the post-treatment ofthe etching, NH₃ gas may be supplied together with the HF gas. The gassupply port 34, the gas supply line 35 for supplying the gas to the gassupply port 34, the valves V1 to V3, the flow rate controllers M1 to M3,and the gas supply sources 36 to 38 constitute the first gas supplyunit. The central gas injection holes 41A, the peripheral gas injectionholes 41B, the valves V4 and V5 for supplying gas to the central gasinjection holes 41A and the peripheral gas injection holes 41B, the flowrate controllers M4 and M5 and the Ar gas supply source 48 constitutethe second gas supply unit. The HF gas and the NH₃ gas may be suppliedfrom any one of the first gas supply unit or the second gas supply unit.The modifying gas may be NH₃ or H₂O.

(Second Embodiment)

A substrate processing apparatus according to a second embodiment willbe described. This substrate processing apparatus has the sameconfiguration as that of the plasma processing apparatus 2 shown in FIG.2 except in the configuration of a shower plate 8 forming a part of thepartition unit 5. The shower plate 8 of the substrate processingapparatus according to the second embodiment will be described withreference to FIGS. 17 to 20. In order to avoid complicated description,the slits 42 penetrating through the shower plate 8 is indicated byblack lines. FIGS. 17 and 18 are plan views of the shower plate 8 whenviewed from the top and the bottom, respectively. FIGS. 19 and 20 arevertical cross sectional views of the shower plate 8 which are takenalong lines I and II shown in FIGS. 17 and 18, respectively.

As shown in FIGS. 17, 19 and 20, a peripheral gas diffusion passage 91for diffusing Ar gas injected from the peripheral portion of the bottomsurface of the shower plate 8 in the right-left direction is formed inthe flange 400 at the front side and the rear side of the shower plate 8on the top surface (facing the plasma space P) of the shower plate 8. Asshown in FIGS. 18 to 20, a central gas diffusion passage 92 fordiffusing Ar gas injected from the central portion of the bottom surfaceof the shower plate 8 in the right-left direction is formed in theflange 400 at the front side and the rear side of the shower plate 8 onthe bottom surface of the shower plate 8. In addition, gas channels 93penetrating through the shower plate 8 in the back-and-forth directionare arranged in the shower plate 8 in the right-left direction. The gaschannels 93 are formed such that the end portions thereof are positionedbelow the peripheral gas diffusion passage 91 at a position higher thana height position where the central gas diffusion passage 92 is formedin the flange 400. In FIGS. 17 and 18, the top surface of the peripheralgas diffusion flow passage 91 and the bottom surface of the central gasdiffusion flow passage 92 are opened. However, as shown in FIGS. 19 and20, the top surface of the peripheral gas diffusion flow and the bottomsurface of the central gas diffusion passage 92 are covered by aplate-shaped member.

In the gas channels disposed at the inner side (the gas channels 93traversing the central region), among the gas channels 93, arranged inthe right-left direction, a gas channel 93 a connected to the peripheralgas diffusion passage 91 through a communication path 96 formed on theupper surface of each of the front end and the rear end of the gaschannel 93 a and a gas channel 93 b connected to the central gasdiffusion passage 92 through a communication path 97 formed on thebottom surface of each of the front end and the rear end of the gaschannel 93 b, are alternately arranged. The gas channels disposed at theouter side (the gas channels 93 not traversing the central region),among the gas channels 93, include only the gas channels 93 a connectedto the peripheral gas diffusion passage 91 through the communicationpath 96 formed on the upper surface of each of the front end and therear end of the gas channel 93 a.

As shown in FIGS. 18 and 19, each of the gas channels 93 a connected tothe peripheral gas diffusion passage 91 has a plurality of injectionholes 95 formed in the peripheral region of the bottom surface of theshower plate 8. As shown in FIGS. 18 and 20, each of the gas channels 93b connected to the central gas diffusion passage 92 has a plurality ofinjection holes 94 formed in the central region of the bottom surface ofthe shower plate 8.

The peripheral gas diffusion passage 91 is connected to the peripheralgas introduction port 403 via the connection passage 404 and theperipheral gas introducing passage 405, as in the case of the peripheralgas diffusion passage 45 of the shower plate 4 shown in FIG. 6. Theperipheral gas supply line 49 shown in FIG. 6, for example, is connectedto the peripheral gas introduction port 403 and Ar gas is supplied tothe gas channel 93 a via the peripheral gas diffusion passage 91. Thecentral gas diffusion passage 92 is also connected to the central gasintroducing port 402 via the connection passage 406 and the central gasintroduction path 407. As in the case of the connection passage 404, theconnection passage 406 is perpendicular to the central gas introductionpath 407 and the central gas diffusion passage 92. The width of theconnection passage 406 is smaller than the width of the central gasintroduction path 407, and the length of the connection passage 406 isgreater than the width of the connection passage 406 by twice or more.

The central gas supply line 47 shown in FIG. 6, for example, isconnected to the central gas introducing port 402 and Ar gas is suppliedto the gas channel 93 b via the central gas diffusion passage 92. Theslits 42 for supplying a first gas, e.g., radicals, excited in theplasma space P to the processing space S are formed at the gap betweenthe adjacent gas channels 93 (93 a and 93 b) in the shower plate 8.

As in the case of the shower plate 4 shown in the first embodiment, inthe shower plate 8, the gas supplied from the peripheral gas supply line49 is diffused by the peripheral gas diffusion passage 91 such that theflow rate becomes uniform in the arrangement direction of the gaschannels 93 a and then supplied to the gas channels 93 a. The gassupplied from the central gas supply line 47 is diffused in the centralgas diffusion passage 92 such that the flow rate becomes uniform in thearrangement direction of the gas channels 93 b and then supplied to thegas channels 93 b. Therefore, not only the gas supplied to theperipheral region of the shower plate 8 but also the flow rate of thegas supplied to the central region become uniform in the arrangementdirection of the gas channel 93 b (the right-left direction).

Accordingly, the second gas supplied from the center region of theshower plate 8 and the second gas supplied from the peripheral regioncan be uniformly injected. As a result, the in-plane distribution of thesecond gas supplied to the central portion and the peripheral portion ofthe wafer W can become uniform and the in-plane uniformity of the secondgas supplied to the wafer W can be more accurately adjusted.

(Third Embodiment)

In the present invention, there may be employed a substrate processingapparatus including a diffusion space where gases are pre-mixed, insteadof a plasma space where a gas is turned into a plasma. Hereinafter, asubstrate processing apparatus for performing processing by supplyinggases, e.g., NF₃ gas, Ar gas, O₂ gas, H₂ gas and the like, which havebeen pre-mixed into the processing space and supplying a gas for postmix, e.g., HF gas, NH₃ gas or the like, directly to the processingspace, will be described. The gas treatment unit for performing gastreatment on the wafer W may have a configuration in which twoprocessing chambers 20 are connected as in the case of theabove-described plasma processing apparatus. Here, an example in which asingle processing chamber 210 is provided will be described. As shown inFIG. 21, the substrate processing apparatus includes a cylindricalprocessing chamber 210 and a shower head 7 provided at a ceiling plateof the processing chamber 210. Reference numerals 21 and 22 denote agate valve and a transfer port, respectively. Reference numerals 61, 62and 6 denote a gas exhaust port, a gas exhaust line and a vacuumevacuation unit, respectively, which are the same as those of the plasmaprocessing apparatus 2. A mounting table 3 is provided in the processingchamber, as in the case of the plasma processing apparatus 2.

The configuration of the shower head 7 will be described with referenceto FIGS. 21 to 23. The shower head 7 includes a diffusion member 71defining a diffusion space D for diffusing the first gas and a showermember 72 for injecting a gas into the processing space S. As shown inFIG. 21, the shower head 72 and the diffusion member 71 are stacked inthat order from the mounting table 3 side. A bottom plate 71 a of thediffusion member 71 and the shower member 72 correspond to a partitionunit for partitioning the processing space S for processing the wafer Wand the diffusion space D for diffusing a gas. FIGS. 21 to 23 areschematic diagrams, and the arrangement and the number of the injectionholes are not accurately illustrated.

As shown in FIGS. 21 and 22, the diffusion member 71 is formed in a flatcylindrical shape in which a diffusion chamber for diffusing a gas isformed. A downstream end portion of the first gas supply line 73 forsupplying the first gas, e.g., NF₃ gas, Ar gas, O₂ gas, H₂ gas or thelike, into the diffusion member 71 is connected to the top plate of thediffusion member 71. Holes 74 for injecting the gas diffused in thediffusion member 71 are formed through the bottom plate 71 a of thediffusion member 71. A first gas supply source 85 for mixing gases suchas NF₃ gas, Ar gas, O₂ gas, H₂ gas and the like and supplying a mixturethereof to the first gas supply line 73 is connected to the upstreamside of the first gas supply line 73. In FIG. 21, notations V6 and M6denote a valve and a flow rate controller, respectively. In thisexample, the first gas is supplied through a single gas inlet into thediffusion member 71. However, it is also possible to introduce aplurality of gases into the diffusion space D through respectiveindividual gas inlets, for example. In that case, the plurality of gasesmay be mixed in the diffusion space D.

As shown in FIGS. 21 and 22, central gas supply lines 75 are provided ata central portion in the diffusing member 71 when viewed from the top.The central gas supply line 75 is configured to supply the second gasfor post mix, e.g., HF gas, NH₃ gas or the like, which through thesecond gas supply line 76 connected to the top plate of the diffusionmember 71, to the central region of the shower member 72 to be describedlater without being diffused in the diffusion space. Further, peripheralgas supply lines 77 are provided at a peripheral portion in thediffusion member 71. The peripheral gas supply line 77 is configured tosupply the second gas, which is fed through the second gas supply line78 connected to the top plate, to the peripheral region of the showermember 72 to be described later without being diffused in the diffusionspace. A reference numeral 86 denotes a second gas supply source of thesecond gas for post mix, such as HF gas, NH₃ gas, or the like. NotationsV4 and V5 in FIG. 21 denote valves provided in the second gas supplylines 76 and 78, respectively. Notations M4 and M5 denote flow ratecontrollers provided in the second gas supply lines 76 and 78,respectively.

As shown in FIGS. 21 and 23, the shower member 72 is a cylindricalmember having a flat bottom. A shower space is formed by closing anupper portion of the shower member 72 by the bottom plate 71 a of thediffusion member 71. The shower space is partitioned into a centralregion and a peripheral region by a partition wall 81. The second gassupplied to the shower space through the central gas supply line 75 ofthe diffusion member 71 flows into the central region surrounded by thepartition wall 81 in the shower space as indicated by dashed arrows inFIG. 21. Then, the second gas flows into the processing space S throughcentral gas injection holes 82 formed in the bottom surface of thecentral region surrounded by the partition wall 81 and then is injectedtoward the wafer W mounted on the mounting table 3.

The second gas supplied to the shower space through the peripheral gassupply line 77 of the diffusion member 71 flows into the peripheralregion outer than the partition wall 81 in the shower space, asindicated by dashed-dotted arrows in FIG. 21. Then, the second gas flowsinto the processing space S through peripheral gas injection holes 83formed in the bottom surface of the peripheral region outer than thepartition wall 81 and then is injected toward the wafer W mounted on themounting table 3.

Gas supply lines 84 are provided in the shower space to correspond tothe holes 74 formed in the bottom plate 71 a of the diffusion member 71.As indicated by solid arrows in FIG. 21, the first gas dischargedthrough the holes 74 of the diffusion member 71 is injected downwardfrom the shower member 72 without being diffused in the shower space.The holes 74 and the gas supply lines 84 correspond to the first gasinjection holes. In this substrate processing apparatus as well, thefirst gas can be diffused in the diffusion space D and injected into theprocessing space S, and the second gas can be independently suppliedinto the processing space S from the central region and the peripheralregion in the shower member 72 without passing through the diffusionspace. Therefore, the concentration distribution of the second gas inthe processing chamber 20 can be adjusted. Accordingly, the same effectcan be obtained.

While the present disclosure has been shown and described with respectto the embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the scope of the present disclosure as defined in the followingclaims.

What is claimed is:
 1. A substrate processing apparatus for processing asubstrate mounted on a mounting table in a processing chamber bysupplying a gas to the substrate, the apparatus comprising: a partitionunit provided, between a processing space where a substrate is providedand a diffusion space where a first gas is diffused, to face themounting table; a first gas supply unit configured to supply the firstgas to the diffusion space; a plurality of first gas injection holesformed through the partition unit in a thickness direction thereof andconfigured to inject the first gas diffused in the diffusion space intothe processing space; and a second gas supply unit including a pluralityof second gas injection holes opened on a gas injection surface of thepartition unit which faces the processing space and configured toindependently supply a second gas to each of a plurality of regionsarranged in a horizontal direction in the processing space separatelyfrom the first gas, wherein the plurality of regions includes a centralregion about a central axis of the substrate and a peripheral regionsurrounding the central region, wherein the second gas supply unitincludes a central gas supply unit configured to supply the second gasto the central region and a peripheral gas supply unit configured tosupply the second gas to the peripheral region, wherein the partitionunit is a plate-shaped body, wherein the central gas supply unitincludes a gas introducing port for a central region formed in aperipheral portion of the plate-shaped body and a central gas channelfor the central region where the second gas injection holes are opened,the central gas channel having one end formed in the plate-shaped bodyto communicate with the gas introducing port for the central region andanother end led to the central region of the plate-shaped body along thegas injection surface, and wherein the peripheral gas supply unitincludes a gas introducing port for a peripheral region formed in aperipheral portion of the plate-shaped body and a peripheral gas channelfor the peripheral region where the second gas injection holes areopened, the peripheral gas channel having one end formed in theplate-shaped body to communicate with the gas introducing port for theperipheral region and the other end led to the peripheral region of theplate-shaped body along the gas injection surface.
 2. The substrateprocessing apparatus of claim 1, wherein the other end of the centralgas channel is led to the central region of the plate-shaped body andthe central gas channel is branched in the central region.
 3. Thesubstrate processing apparatus of claim 1, wherein the central gaschannel includes a plurality of central gas channels and the peripheralgas channel includes a plurality of peripheral gas channels, wherein agas diffusion passage for the central region through which a gas isdiffused and supplied to each of the central gas channels and a gasdiffusion passage for the peripheral region through which a gas isdiffused and supplied to each of the peripheral gas channels areprovided at different height positions of the partition unit, and aheight direction of the partition unit is set to a thickness directionof the partition unit, wherein each of the plurality of central gaschannels and each of the plurality of peripheral gas channels areextending along the gas injection surface, and wherein the plurality ofcentral gas channels and the plurality of peripheral gas channels arearranged in the partition unit in the horizontal direction.
 4. Thesubstrate processing apparatus of claim 1, wherein the first gas is aprocessing gas for processing a substrate and the second gas is an inertgas.
 5. The substrate processing apparatus of claim 1, furthercomprising: a plasma generation unit configured to activate the firstgas supplied into the diffusion space.
 6. The substrate processingapparatus of claim 5, further comprising: an ion trap unit providedcloser to the diffusion space compared to the first gas injection holesand having therein a gas channel communicating with the first gasinjection holes, the ion trap unit serving to trap ions in the activatedfirst gas.
 7. The substrate processing apparatus of claim 6, wherein thepartition unit includes a heat shield member configured to suppresstransfer of heat of the ion trap unit to the processing space.
 8. Thesubstrate processing apparatus of claim 7, wherein the heat shieldmember and the processing chamber are made of metal and brought intocontact with each other.
 9. The substrate processing apparatus of claim7, wherein in the partition unit, a gas channel through which the secondgas flows is formed through the heat shield member.
 10. The substrateprocessing apparatus of claim 5, wherein the first gas serves as anetching gas for etching a silicon nitride film formed on a surface ofthe substrate, and the second gas serves as a distribution adjusting gasfor adjusting distribution of the first gas in the processing space. 11.The substrate processing apparatus of claim 10, wherein an oxide filmremoving gas for removing an oxide film on a surface of the siliconnitride film before or after the etching is supplied from the first gassupply unit into the processing space through the diffusion space or issupplied from the second gas supply unit into the processing space. 12.The substrate processing apparatus of claim 10, wherein the first gassupply unit supplies a modifying gas for modifying the silicon nitridefilm into the diffusion space before the etching gas is supplied intothe diffusion space, and the plasma generation unit activates themodifying gas.
 13. A substrate processing method for the substrateprocessing apparatus disclosed in claim 1, the method comprising:etching a silicon nitride film formed on a surface of the substrate byactivating the first gas supplied into the diffusion space and supplyingthe activated first gas into the processing space; adjustingdistribution of the activated first gas in the processing space bysupplying the second gas to the plurality of regions in the processingspace; and supplying an oxide film removing gas for removing an oxidefilm on the surface of the silicon nitride film from the first gassupply unit to the processing space through the diffusion space or fromthe second gas supply unit to the processing space.
 14. The substrateprocessing method of claim 13, further comprising: between said etchingand said adjusting, supplying an oxide film removing gas for removing anoxide film on the surface of the substrate from the first gas supplyunit to the processing space through the diffusion space or from thesecond gas supply unit to the processing space.
 15. The substrateprocessing method of claim 13, further comprising: between said etchingand said adjusting, supplying a modifying gas for modifying the siliconnitride film into the diffusion space from the first gas supply unit;and activating the modifying gas and supplying the activated modifyinggas to the substrate.
 16. The substrate processing apparatus of claim 1,wherein the central gas supply unit includes a connection passage forthe central region to connect the gas introducing port for the centralregion to the gas diffusion passage for the central region, theconnection passage for the central region is perpendicular to the gasintroducing port for the central region and the gas diffusion passagefor the central region, the peripheral gas supply unit includes aconnection passage for the peripheral region to connect the gasintroducing port for the peripheral region to the gas diffusion passagefor the peripheral region, and the connection passage for the peripheralregion is perpendicular to the gas introducing port for the peripheralregion and the gas diffusion passage for the peripheral region.
 17. Thesubstrate processing apparatus of claim 16, wherein a width of theconnection passage for the central region is smaller than a width of thegas introducing port for the central region, and a length of theconnection passage for the central region is greater than the width ofthe connection passage for the central region by twice or more, a widthof the connection passage for the peripheral region is smaller than awidth of the gas introducing port for the peripheral region, and alength of the connection passage for the peripheral region is greaterthan the width of the connection passage for the peripheral region bytwice or more.
 18. The substrate processing apparatus of claim 3,wherein the plurality of central gas channels and the plurality ofperipheral gas channels are positioned between the gas diffusion passagefor the central region and the gas diffusion passage for the peripheralregion in the height direction.